Bubonic Plague Increased Immunity in Future Generations, Research Suggests
Exposure to the bubonic plague — a devastating global pandemic that ravaged parts of Europe and Asia in the 1300s — might have had a long-term impact on the immunity levels among later generations, according to a new study.
The bubonic plague outbreak, also known as the Black Death, was caused by a pathogen called Yersinia pestis. The study, published in Molecular Biology and Evolution, found that future generations of the victims had better immunity against the bacteria. “It sheds light on our own evolution,” Paul Normal, from the Department of Immunology and Microbiology at the University of Colorado School of Medicine in the U.S., who co-authored the study, said in a statement. The plague resulted in the deaths of almost a third of the European population, along with striking countries like China, Egypt, and India.
To understand how immunity developed over time, the researchers studied the remains of 36 victims from a mass grave in a German town. They collected DNA samples from 50 residents who currently live in the same town where the graveyard is located. “We found that innate immune markers increased in frequency in modern people from the town compared to plague victims — this suggests these markers might have evolved to resist the plague,” Norman added. The research indicates an evolutionary capacity in our genes, which potentially built resistance against the virus.
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Does this discovery tell us anything about Covid19, a pandemic that has killed over 3 million people globally? Possibly. The researchers found evidence that the exposure of our ancestors to the pathogen Yersinia pestis prompted changes in our genetic structures to help our bodies initiate and direct immune responses to the infection. And the researchers believe that focusing on the same genes that enabled us to fight the bubonic plague may help our understanding of immunity in itself.
“We know these genes were heavily involved in driving resistance to infections,” Norman said. “I think this study shows that we can focus on these same families of genes in looking at immunity in modern pandemics.”
According to the authors, the fact that two-thirds of Europeans still survived the plague — the most fatal pandemic in recorded history — suggests that some people may simply be less prone to the severity of infections because of their genetic structures — no matter how deadly the infection may be. “There will always be people who have some resistance. They just don’t get sick and die and the human population bounces back,” he noted.
But he also strongly cautioned people against relying on their genetic resistance to get through the ongoing Covid19 pandemic. Evidence about immunity against SARS-CoV-2, the coronavirus responsible for Covid19, is still unfolding as new information about mutations, variants, and reinfections continues to come to light. When it comes to efficacy in fighting the virus, vaccinations remain the most pivotal way. “I wouldn’t want to discourage anyone from taking a vaccine for the current pandemic — it’s a much safer bet than counting on your genes to save you,” Norman says.
Update: A previous version of this article had incorrectly made one reference to Yersinia pestis as a virus.